<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<HTML>
<HEAD>
<TITLE>80386 Programmer's Reference Manual -- Opcode ADD</TITLE>
</HEAD>
<BODY STYLE="width:80ch">
<B>up:</B> <A HREF="c17.htm">
Chapter 17 -- 80386 Instruction Set</A><BR>
<B>prev:</B><A HREF="ADC.htm"> ADC Add with Carry</A><BR>
<B>next:</B><A HREF="AND.htm"> AND Logical AND</A>
<P>
<HR>
<P>
<H1>ADD -- Add</H1>

<PRE>
Opcode    Instruction         Clocks    Description

04 ib     ADD AL,imm8          2        Add immediate byte to AL
05 iw     ADD AX,imm16         2        Add immediate word to AX
05 id     ADD EAX,imm32        2        Add immediate dword to EAX
80 /0 ib  ADD r/m8,imm8        2/7      Add immediate byte to r/m byte
81 /0 iw  ADD r/m16,imm16      2/7      Add immediate word to r/m word
81 /0 id  ADD r/m32,imm32      2/7      Add immediate dword to r/m dword
83 /0 ib  ADD r/m16,imm8       2/7      Add sign-extended immediate byte
                                        to r/m word
83 /0 ib  ADD r/m32,imm8       2/7      Add sign-extended immediate byte
                                        to r/m dword
00 /r     ADD r/m8,r8          2/7      Add byte register to r/m byte
01 /r     ADD r/m16,r16        2/7      Add word register to r/m word
01 /r     ADD r/m32,r32        2/7      Add dword register to r/m dword
02 /r     ADD r8,r/m8          2/6      Add r/m byte to byte register
03 /r     ADD r16,r/m16        2/6      Add r/m word to word register
03 /r     ADD r32,r/m32        2/6      Add r/m dword to dword register
</PRE>

<H2>Operation</H2>

<PRE>
DEST := DEST + SRC;
</PRE>

<H2>Description</H2>

ADD performs an integer addition of the two operands (DEST and SRC). The
result of the addition is assigned to the first operand (DEST), and the
flags are set accordingly.
<P>
When an immediate byte is added to a word or doubleword operand, the
immediate value is sign-extended to the size of the word or doubleword
operand.

<H2>Flags Affected</H2>

OF, SF, ZF, AF, CF, and PF as described in <A HREF="appc.htm">Appendix C</A>

<H2>Protected Mode Exceptions</H2>

#GP(0) if the result is in a nonwritable segment; #GP(0) for an illegal
memory operand effective address in the CS, DS, ES, FS, or GS segments;
#SS(0) for an illegal address in the SS segment; #PF(fault-code) for a page
fault

<H2>Real Address Mode Exceptions</H2>

Interrupt 13 if any part of the operand would lie outside of the effective
address space from 0 to 0FFFFH

<H2>Virtual 8086 Mode Exceptions</H2>

Same exceptions as in Real Address Mode; #PF(fault-code) for a page fault


<P>
<HR>
<P>
<B>up:</B> <A HREF="c17.htm">
Chapter 17 -- 80386 Instruction Set</A><BR>
<B>prev:</B><A HREF="ADC.htm"> ADC Add with Carry</A><BR>
<B>next:</B><A HREF="AND.htm"> AND Logical AND</A>
</BODY>
